I started presenting on the subject of VDWhy a long time ago, all over the world. It never seems to have been recorded though. A Quest partner has published a video of it though, feel free to take a look.
The video covers me going through a powerpoint deck where discuss the real-world reasons for choosing VDI , TS or none of them. It is fairly technical but I have had good feedback on sessions like these (VMworld Europe was a good example).
Watch the video here: http://www.agreeya.com/vdwhy_videos.shtml